Cyclopentenes which are substituted with various hydrocarbyl groups can be homopolymerized or copolymerized with cyclopentene itself to form polymers useful as molding resins. Nickel and palladium xcex1-diimine complexes can be used as catalysts for these polymerizations, but also disclosed herein are xcex1-diimine complexes which are novel catalysts for the polymerization of cyclopentenes.
Nickel and palladium xcex1-diimine complexes are known catalysts for the polymerization of various olefins, including cyclopentene itself, see for instance World Patent Application 96/23010. However, methods for polymerization of various substituted cyclopentenes have not been reported with such catalysts.
Homopolymers of 3-methylcyclopentene have been reported, see for instance J. Boor, et al., Die Makromolekulare Chemie, vol. 90, p. 26-37 (1966).
World Patent Applications 96/23010 and 98/27124, and U.S. Pat. No. 5,880,241 describe homopolycyclopentenes which are melt processible.
This invention concerns a polymer, comprising, repeat units derived from one or more of 3-methylcyclopentene, 4-methylcyclopentene, 3-ethylcyclopentene or 3-cyclopentylcyclopentene, and optionally cyclopentene, provided that when said polymer is a homopolymer of 3-methylcyclopentene, at least about 40 mole percent of repeat units present are of the formula 
This invention also concerns a process for the polymerization of one or more olefins selected from the group consisting of 3-methylcyclopentene, 4-methylcyclopentene, 3-ethylcyclopetnene and 3-cyclopentylcyclopentene, and optionally cyclopentene, by contacting, at a temperature of xe2x88x92100xc2x0 C. to about +200xc2x0 C., said olefin with a olefin polymerization catalyst system containing a nickel or palladium complex of a compound of the formula 
and optionally other cocatalysts, wherein
R2 and R5 are each independently hydrocarbyl or substituted hydrocarbyl, provided that the carbon atom bound to the imino nitrogen atom has at least two carbon atoms bound to it; and
R3 and R4 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or R3 and R4 taken together are hydrocarbylene or substituted hydrocarbylene to form a carbocyclic ring.
Disclosed herein is a compound of the formula 
wherein:
each X is independently an anion;
n is 2 or 3;
R3 and R4 taken together are 
R5, R6, R7, R8, R9, R10, R11, R12, R13, and R14 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group;
and provided that:
when R5 is the same as R10, and R9 is the same as R14, said compound is in an anti form;
no more than one of R5, R9, R10, and R14 is hydrogen;
any two of R5, R6, R7, R8, R9, R10, R11, R12, R13, and R14 vicinal to one another may form a ring; and
R5 is different than R9.
This invention also concerns a process for the polymerization of one or more of cyclopentene and a substituted cyclopentene, comprising, contacting, at a temperature of xe2x88x92100xc2x0 C. to about +200xc2x0 C., said olefin with a olefin polymerization catalyst system containing a compound of the formula 
and optionally cocatalysts, wherein:
each X is independently a monoanion;
n is 2 or 3;
R3 and R4 taken together are 
R5, R6, R7, R8, R9, R10, R11, R12, R13, and R14 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group;
and provided that:
when R5 is the same as R10, and R9 is the same as R14, said compound is in an anti form;
no more than one of R5, R9, R10, and R14 is hydrogen;
any two of R5, R6, R7, R8, R9, R10, R11, R12, R13, and R14 vicinal to one another may form a ring; and
R5 is different than R9.
This invention also concerns a homopolycyclopentene that has an end of melting point of 325xc2x0 C. to about 380xc2x0 C.
Herein certain terms are used to define certain chemical groups or compounds. These terms are defined below.
A xe2x80x9chydrocarbyl groupxe2x80x9d is a univalent group containing only carbon and hydrogen. If not otherwise stated, it is preferred that hydrocarbyl groups herein contain 1 to about 30 carbon atoms.
By xe2x80x9csubstituted hydrocarbylxe2x80x9d herein is meant a hydrocarbyl group which contains one or more substituent groups which are inert under the process conditions to which the compound containing these groups is subjected. The substituent groups also do not substantially interfere with the process. If not otherwise stated, it is preferred that substituted hydrocarbyl groups herein contain 1 to about 30 carbon atoms. Included in the meaning of xe2x80x9csubstitutedxe2x80x9d are heteroaromatic rings.
By an alkyl aluminum compound is meant a compound in which at least one alkyl group is bound to an aluminum atom. Other groups such as alkoxide, oxygen, and halogen may also be bound to aluminum atoms in the compound.
By xe2x80x9chydrocarbylenexe2x80x9d herein is meant a divalent group containing only carbon and hydrogen. Typical hydrocarbylene groups are xe2x80x94(CH2)4xe2x80x94, xe2x80x94CH2CH(CH2CH3)CH2CH2xe2x80x94 and 
If not otherwise stated, it is preferred that hydrocarbylene groups herein contain 1 to about 30 carbon atoms.
By xe2x80x9csubstituted hydrocarbylenexe2x80x9d herein is meant a hydrocarbylene group which contains one or more substituent groups which are inert under the process conditions to which the compound containing these groups is subjected. All of the hydrogen atoms may be substituted, as in trifluoromethyl. The substituent groups also do not substantially interfere with the process. If not otherwise stated, it is preferred that substituted hydrocarbylene groups herein contain 1 to about 30 carbon atoms. Included within the meaning of xe2x80x9csubstitutedxe2x80x9d are heteroaromatic rings.
By an (inert) functional groups is meant a functional group that does not substantially interfere with the utility of the compound in which that group is located and does not make that compound unstable to the point where it is not useful for its intended purpose. Useful functional groups include halo and ether.
By xe2x80x9cantixe2x80x9d herein is meant that when R5 is identical to R10, and R9 is identical to R14, the identical groups (i.e., the pairs R5 and R10, and R9 and R14 are on opposite sides of the approximate plane formed by the two carbons and the two nitrogen atoms of the xcex1-diimine grouping and the nickel atom.
In the polymerization process described herein for the substituted cyclopentenes (SCP) using xcex1-diimine complexes of nickel or palladium, the same catalysts compounds and systems and conditions as reported in World Patent Application 96/23010, which is hereby included by reference, are used. Preferred nickel and palladium complexes reported therein, especially those preferred for the polymerization of cyclopentene itself, are preferred for the polymerization of the SCP reported herein. Likewise, preferred conditions, such as temperature and solvent (if used) are also preferred herein. A preferred cocatalysts, as in WO 96/23010 is an alkyl aluminum compound.
The various SCP reported herein polymerize to form one or more xe2x80x9cunusualxe2x80x9d repeat units in the resulting polymer. Rarely if at all does any of the SCP polymerize into the polymer merely by adding across the double bond present in the cyclopentyl ring. Also, there may be a difference between repeat structures obtained using nickel and palladium complexes. The structures of various polymers are described below.
3- and 4-Methylcyclopentene with Pd Catalyst (see Examples 4, 5 and 8). These two monomers give almost identical polymers with Pd catalysts. The majority of the repeat units are 1,3xe2x80x2-trans of the formula 
typically about 80 mole percent of the repeat units. 1,2xe2x80x2-Trans units, 
are also present in minor amounts, typically about 10-25 mole percent of the repeat units. There may also be small amounts of repeat units containing pendant methyl groups, especially from 4-methylcyclopentene.
3-Methylcyclopentene with Ni Catalyst (Example 6). This polymerization gives polymers with substantial amounts (preferably  greater than 40 mole percent, and typically 60 mole percent) of repeat units of the formula (II). Also present are a substantial amount of repeat unit (IX), typically about 40 mole percent of the repeat units. 
4-Methylcyclopentene and Ni Catalyst (Example 13). This gives a polymer containing substantial amounts of repeat units (II) and (IX), typically about 50 mole percent of each.
3-Ethylcyclopentene with Pd Catalyst (Example 9). This polymer has two predominant structures, 1,3xe2x80x2-trans (IV), and 1,2xe2x80x2-trans (V), 
The majority of the repeat units, typically about 75 mole percent are (IV), while a minority, usually a substantial amount, of the repeat units are (V), typically about 25 mole percent.
3-Ethylcyclopentene with Ni Catalyst (Example 12). Structures believed to be present in substantial amounts include (IV) and (VI). Typically (IV) is a majority of the repeat units, often about 70 mole percent, while (VI) is typically about 30 mole percent of the repeat units. 
Cyclopentylcylopentene with Ni Catalyst (Example 2). In this polymer, trans 1,3-cyclopentyl, (VII), is a majority of the repeat unit of the polymer, typically about 80 mole percent, while cis-1,3 enchainment (VIII) is a minor, but usually substantial, portion of the repeat units, typically about 20 mole percent. 
By a xe2x80x9csubstantialxe2x80x9d amount of repeat units herein in any particular polymer is meant at least 10 mole percent of the repeat units.
The homo- and copolymers described herein are useful as thermoplastic molding resins (for those that are crystalline or glassy at ambient conditions) or as elastomers (for those which are rubbery at ambient conditions). In copolymers with cyclopentene, the use of the substituted cyclopentenes allows lowering of the melting point of the polymer, when compared to homopolycyclopentene.
It has been found that in complexes like (X), when none of R5, R9, R10, and R14 are hydrogen, rotation about the Cxe2x80x94N bond of the aryl groups is hindered. Therefore, when R5 is the same as R10, and R9 is the same as R14 the complex can exist and be isolated as either syn or anti isomers. (X) is the anti form of the compound. It is preferred that R5, R9, R10, and R14 are hydrocarbyl, substituted hydrocarbyl, or halo. In another preferred embodiment, R5, R9, R10, and R14 are all alkyl and it is more preferred that R5 and R10 are methyl, and R9 and R14 are identical alkyl groups having 2 or more carbons, especially preferably R9 and R14 are isopropyl. It is also preferred that X is halide and/or n is 2. It is also preferred that in (X) R3 and R4 taken together are (An).
(X) can be made by methods described in World Patent Application 96/23010. The anti isomer may be isolated by fractional crystallization.
In the polymerization process described herein using (X), the same catalyst system and conditions as reported in World Patent Application 96/23010 for xcex1-diimine complexes, which is hereby included by reference, are used. Preferred structures are also reported therein, especially those preferred for the polymerization of cyclopentene itself, and are also preferred for the polymerization using (X). Likewise, preferred conditions, such as temperature and solvent (if used) are also preferred herein. A preferred cocatalyst, as in WO 96/23010 is an alkyl aluminum compound.
Compounds such as (X), when polymerizing cyclopentene, give a polymer which has properties that are often different from those polymers obtained with other xcex1-diimine nickel complexes. For example, at equivalent conditions, the melting point tends to be somewhat higher. This is believed to be due to a different mechanism of stereoregulation by these complexes compared to other nickel xcex1-diimine complexes. Other xcex1-diimine nickel complexes produce partially isotactic polycyclopentene by a chain end control mechanism. (Stephan J. McLain et. al., Macromolecules, Volume 31, Number 19, pages 6705-6707, 1998). By studying the hydrooligomerization reaction by the method described in this reference, we have found that surprisingly, compounds (X) give enantiosite control of the polymerization instead of the chain-end control of stereochemistry observed with xcex1-diimine Ni complexes. We believe this mechanism of stereocontrol produces longer isotactic segments in the partially isotactic polymer, thus leading to higher melting points. If the polymerization temperature is raised, the melting point of polycyclopentene made by any xcex1-diimine nickel complex will usually decrease. It is usually desirable to run polymerizations at higher temperatures because the rates usually increase with temperature. Thus a balance often needs to be struck between polymerization rate and polymer melting point. An advantage of (X) when R3 and R4 taken together are (An) is that it can be used at a higher polymerization temperature and still produce a polymer with a relatively high melting point, although the polymer will have a melting point that is lower than obtained at lower reaction temperatures.
In the Examples, the following convention is used for naming xcex1-diimine complexes of metals, and the xcex1-diimine itself. The xcex1-diimine is indicated by the letters xe2x80x9cDABxe2x80x9d. To the left of the xe2x80x9cDABxe2x80x9d are the two groups attached to the nitrogen atoms, herein often called R2 and R5. To the right of the xe2x80x9cDABxe2x80x9d are the groups on the two carbon atoms of the xcex1-diimine group, herein usually termed R3 and R4. To the right of all this appears the metal, ligands attached to the metal and finally any anions (X).
In the Examples the following abbreviations are used:
3-EtCypxe2x80x943-ethylcyclopentene
3-MeCypxe2x80x943-methylcyclopentene
4-MeCypxe2x80x944-methylcyclopentene
BAFxe2x80x94tetrakis[3,5-bis(trifluoromethyl)phenyl]borate
DSC: Differential Scanning Calorimetry
Hfxe2x80x94heat of fusion (melting)
MeOHxe2x80x94Methanol
PMAOxe2x80x94polymethylaluminoxane
RTxe2x80x94room temperature
TCBxe2x80x941,2,4-trichlorobenzene
Tgxe2x80x94glass transition temperature
TGAxe2x80x94thermogravimetric analysis
Tmxe2x80x94melting point
The following describes generally some of the techniques used in determining the structures of the polymers described herein.
INADEQUATE (Incredible Natural Abundance DoublE QUAntum Transfer Experiment):
This 2D NMR technique gives information on connectivities between carbon atoms. The 2D contour map shows correlations between carbons and their double quantum frequencies. Carbons which share the same double quantum frequency (have correlations on the same ROW of the 2D plot) are connected by covalent bonds. This is a 13C observe experiment with VERY LOW signal to noise, and can take 4 days per sample.
HMQC (Heteronuclear Multiple Quantum Coherence):
This 2D NMR technique gives information on connectivities between carbons and protons that are directly bonded to each other. The correlations in the 2D contour plot connect each proton signal with the carbon signal for the carbon covalently bonded to that proton. This is a high signal-to-noise very quick 1H NMR observe experiment. The digital resolution is best in the 1H dimension.
HSQC (Heteronuclear Single Quantum Coherence):
The 2D NMR experiment gives basically the same results as the HMQC experiment, but is sometimes better for polymers which have shorter relaxation time constants.
HETCOR (HETeronuclear CORrelation):
This 2D NMR technique gives information on connectivities between carbons and protons that are directly bonded to each other. The correlations in the 2D contour plot connect each carbon signal with the proton signal for the proton covalently bonded to that carbon. This is a low signal-to-noise 13C observe experiment. The digital resolution is best in the 13C dimension.
HMBC (Heteronuclear Multiple Bond Correlation):
This 2D NMR technique gives information on connectivities between carbons and protons that are separated by two and/or three covalent bonds. The correlations in the 2D contour plot connect each proton signal with the carbon signal for the carbons that are two and/or three bonds separated from that proton. This is a medium signal-to-noise 1H NMR observe experiment and requires magnetic field gradients to be really successful. The digital resolution is best in the 1H dimension. The carbon does not need to carry a proton making this a useful adjunct to the HMQC-TOCSY experiment.
TOCSY TOtal Correlation SpectroscopY):
This 2D NMR technique gives information on all the protons in a particular neighborhood. How big the neighborhood is depends on the length of the NMR spin lock that is used in the experiment, and can be adjusted. The neighborhood encompasses a group of protons that are pairwise on neighboring carbons and are pairwise spin coupled to each other. A quaternary carbon, ether, carbonyl, etc., interrupts the chain of protons on neighboring carbons and limits the neighborhood. This is a high signal to noise 1H observe experiment.
HMQC-TOCSY (or HSQC-TOCSY)
This experiment combines the HMQC (or HSQC) and TOCSY experiments together. The result is that each proton shows correlations to all the protonated carbons in its neighborhood, thus defining a GROUP of carbons that are pairwise covalently bonded. This is a medium signal-to-noise 1H NMR observe experiment. The digital resolution is best in the 1H dimension. This is one of the most useful experiments as it groups both the protons and carbons that belong in a particular area or microstructure of the polymer.
COSY (COrrelation SpectroscopY):
This 2D NMR technique gives information on protons that are spin coupled to each other, generally on neighboring carbons or 4 bonds apart. This is a high signal-to-noise very quick 1H NMR observe experiment.
DEPT (Distortionless Enhancement by Polarization Transfer):
This 1 D multipulse NMR experiment gives information on the number of protons attached to each carbon atom. Carbons with one or three protons attached are positive, carbons with two protons attached are negative, and carbons without any protons are not observed in this experiment. This is a 13C observed experiment, but the signal to noise is very high because magnetization is transferred from the protons and because the scans can be repeated according to the proton (not the carbon, which is slower) relaxation time.
The melting point of the polymers, particularly homopolycyclopentene, are determined by Differential Scanning Calorimetry at a heating rate of 15xc2x0 C./min (except as otherwise noted, but this rate is the rate applicable in the claimsxe2x80x94lower heating rates tend to give somewhat lower melting points, and higher heating rates tend to give somewhat lower melting points), and taking the maximum of the melting endotherm as the melting point. However these polymers tend to have relatively diffuse melting points, so it is preferred to measure the xe2x80x9cmelting pointxe2x80x9d by the end of melting point. The method is the same, except the end of melting is taken as the end (high temperature end) of the melting endotherm which is taken as the point at which the DSC signal returns to the original (extrapolated) baseline. If not stated as an end of melting point the melting point has been taken as the peak of the melting endotherm.
3-Methylcyclopentene (3-MeCyp); prepared according to Nugent et. al. (J. Am. Chem. Soc., 1995, vol. 117, p. 8992) was degassed and stored in a drybox over 5 xc3x85 molecular sieves.
3-Ethylcyclopentene (3-EtCyp) (Wiley Organics, 99%) was degassed and taken into a nitrogen purged drybox. It was then run through alumina and stored over 5 xc3x85 molecular sieves.
4-Methylcyclopentene (4-MeCyp) (Carnagie Mellon University-American Petroleum Institute standards) was used as received.
Cyclopentylcylopentene was obtained from Chemsampco.